间甲酚溶液中掺杂聚苯胺的氧化-还原行为研究

STUDIES ON REDOX BEHAVIOR OF DOPED POLYANILINE IN m-CRESOL SOLUTIONS

在有、无外加恒定磁场(0.4T)条件下,采用乳液聚合法合成了十二烷基苯磺酸掺杂聚苯胺(PAn),通过傅立叶红外光谱(FT-IR)、在有/无外电场作用下产物/m-cresol溶液的电导率、pH及其颜色随温度变化的分析表征,系统研究了温度对PAn/m-cresol溶液中PAn氧化-还原(掺杂-脱掺杂)行为的影响.溶液电导率和pH的测试结果显示,溶液电导率与溶液中游离掺杂酸的浓度成正比,PAn的掺杂度随温度的升高而降低,随温度的降低而增大,且在相同温度下,有、无外电场作用时PAn/m-cresol溶液的电导率存在突跃.与无磁场条件下合成的PAn所制备的m-cresol溶液相比,磁场条件下合成的PAn所制备的m-cresol溶液电导率的突跃更加显著.经脱掺杂处理后的PAn/m-cresol溶液的电导率均较低,对温度变化的响应极其微弱,且在有、无外电场作用时不发生突跃.分析认为,这是由于外电场作用下m-cresol溶液中掺杂态的PAn分子发生了取向重排,而脱掺杂的PAn则无此变化.PAn在外电场作用下的取向重排及氧化-还原性均与其掺杂程度相关,掺杂程度越高,氧化-还原及取向重排越显著.

Polyaniline （PAn） doped with dodecyl benzene sulfonic acid （DBSA） was synthesized by emulsion polymerization of aniline under the presence and absence of a constant magnetic field （0.4T）.The effects of temperature on the redox （doping-dedoping） behavior of PAn in PAn/m-cresol solutions were systematically investigated by characterization and analysis of FT-IR spectroscopy,conductivity change of the product/m-cresol solution with temperature under the presence and absence of an external electric field,the changes of pH and colors of the solution.The measurement results of the pH and conductivity in the PAn/m-cresol solution showed that the conductivity of the PAn/m-cresol solution was directly proportional to the concentration of the dissociative doping acid getting away from PAn,and the dedoping degree of PAn was enhanced with the temperature increasing and lowered with the temperature decreasing.Moreover,the PAn/m-cresol solution showed obvious abrupt change in its conductivity from the presence of external electric field to its absence at same temperature.Compared with the abrupt conductivity change in the m-cresol solution of PAn synthesized under the absence of magnetic field,the abrupt conductivity change in the m-cresol solution of PAn synthesized under the presence of magnetic field was more remarkable.However,the conductivities of the m-cresol solutions prepared from dedoped PAn were generally low and inert to the changes of temperature and they never underwent abrupt change in their conductivity from the presence of external electric field to its absence at same temperature.It was thought that because under the presence of an external electric field there was an oriented rearrangement of doped PAn in the m-cresol solution,but not for the dedoped PAn.Moreover,not only the oriented rearrangement under external electric field but also the redox behavior of PAn were related to doping level,the greater the doping level,the more remarkable the special behaviors.